Condenser with external subcooler

ABSTRACT

Embodiments of the present disclosure relate to a vapor compression system that includes a refrigerant loop, a compressor disposed along the refrigerant loop and configured to circulate refrigerant through the refrigerant loop, a condenser disposed downstream of the compressor along the refrigerant loop and configured to condense vapor refrigerant to liquid refrigerant, a subcooler coupled to the condenser, where the subcooler is external of a shell of the condenser, and where the subcooler is configured to receive the liquid refrigerant from the condenser and to cool the liquid refrigerant to sub cooled refrigerant, and an evaporator disposed downstream of the subcooler along the refrigerant loop and configured to evaporate the subcooled refrigerant to the vapor refrigerant.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from and the benefit of U.S.Provisional Application Ser. No. 62/270,164, filed Dec. 21, 2015,entitled “VAPOR COMPRESSION SYSTEM,” Chinese Patent Application No.201521134920.9, filed Dec. 31, 2015, entitled “SHELL AND TUBE CONDENSERWITH EXTERNAL SUBCOOLER,” and Chinese Patent Application No.201521138170.2, filed Dec. 31, 2015, entitled “SHELL AND TUBE CONDENSERWITH EXTERNAL SUBCOOLER,” the disclosures of which are herebyincorporated by reference in their entireties for all purposes.

BACKGROUND

This application relates generally to vapor compression systemsincorporated in air conditioning and refrigeration applications.

Vapor compression systems utilize a working fluid, typically referred toas a refrigerant that changes phases between vapor, liquid, andcombinations thereof in response to being subjected to differenttemperatures and pressures associated with operation of the vaporcompression system. Refrigerants are desired that are friendly to theenvironment, yet have a coefficient of performance (COP) that iscomparable to traditional refrigerants. COP is a ratio of heating orcooling provided to electrical energy consumed, and higher COPs equateto lower operating costs. Unfortunately, there are challenges associatedwith designing vapor compression system components compatible withenvironmentally-friendly refrigerants, and more specifically, vaporcompression system components that operate to maximize efficiency usingsuch refrigerants.

SUMMARY

In an embodiment of the present disclosure, a vapor compression systemincludes a refrigerant loop, a compressor disposed along the refrigerantloop and configured to circulate refrigerant through the refrigerantloop, a condenser disposed downstream of the compressor along therefrigerant loop and configured to condense vapor refrigerant to liquidrefrigerant, a subcooler coupled to the condenser, where the subcooleris external of a shell of the condenser, and where the subcooler isconfigured to receive the liquid refrigerant from the condenser and tocool the liquid refrigerant to sub cooled refrigerant, and an evaporatordisposed downstream of the subcooler along the refrigerant loop andconfigured to evaporate the subcooled refrigerant to the vaporrefrigerant.

In another embodiment of the present disclosure, a subcooler includes ashell, a plurality of tubes, where the plurality of tubes are disposedwithin the shell, and an inlet disposed on the shell and configured todirect condensed refrigerant from a condenser into the subcooler, andwhere the subcooler is coupled to an outer shell of the condenser.

In another embodiment of the present disclosure, a vapor compressionsystem includes a refrigerant loop, a compressor disposed along therefrigerant loop and configured to circulate refrigerant through therefrigerant loop, a condenser disposed downstream of the compressoralong the refrigerant loop, where the condenser includes a shell and afirst plurality of tubes disposed in the shell, where the firstplurality of tubes is configured to flow a first cooling fluid, andwhere the first cooling fluid is configured to be in a heat exchangerelationship with the refrigerant, a subcooler coupled directly to anouter surface of the shell of the condenser or coupled indirectly to theouter surface of the shell of the condenser, where the subcoolerincludes a subcooler shell and a second plurality of tubes configured toflow a second cooling fluid, and where the second cooling fluid isconfigured to be in a heat exchange relationship with the refrigerant,and an evaporator disposed downstream of the subcooler along therefrigerant loop.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of an embodiment of a building that mayutilize a heating, ventilation, air conditioning, and refrigeration(HVAC&R) system in a commercial setting, in accordance with an aspect ofthe present disclosure;

FIG. 2 is a perspective view of a vapor compression system, inaccordance with an aspect of the present disclosure;

FIG. 3 is a schematic of an embodiment of the vapor compression systemof FIG. 2, in accordance with an aspect of the present disclosure;

FIG. 4 is a schematic of an embodiment of the vapor compression systemof FIG. 2, in accordance with an aspect of the present disclosure;

FIG. 5 is a perspective view of an embodiment of a condenser of thevapor compression system of FIG. 2 that includes an external subcoolerhaving a shell portion, in accordance with an aspect of the presentdisclosure;

FIG. 6 is a cross section of an embodiment of the condenser having anexternal subcooler directly coupled to a shell of the condenser, inaccordance with an aspect of the present disclosure;

FIG. 7 is a perspective view of the condenser of FIG. 6, in accordancewith an aspect of the present disclosure;

FIG. 8 is a cross section of an embodiment of the condenser of FIG. 6with the external subcooler having a partition plate, in accordance withan aspect of the present disclosure;

FIG. 9 is a cross section of an embodiment of the condenser thatoperates as a two-pass heat exchanger and includes the externalsubcooler, in accordance with an aspect of the present disclosure;

FIG. 10 is a cross section of an embodiment of the condenser thatincludes the external subcooler having a curved cross section, inaccordance with an aspect of the present disclosure; and

FIG. 11 is a cross section of an embodiment of the condenser thatincludes the external subcooler coupled indirectly to the shell of thecondenser via an intermediate conduit, in accordance with an aspect ofthe present disclosure.

DETAILED DESCRIPTION

Embodiments of the present disclosure are directed towards a condenserof a vapor compression system that includes an external subcooler.Typically, the subcooler is positioned within a shell of the condenser.Unfortunately, a relatively large level of refrigerant may be present inthe condenser when the subcooler is included within the condenser toensure that the subcooler sufficiently cools the refrigerant.Additionally, a size of the condenser may be increased to accommodate anadditional volume consumed by the subcooler. Further, manufacturing thecondenser to include the subcooler within the shell may be relativelycomplex, time-consuming, and expensive. Therefore, embodiments of thepresent disclosure are directed to a condenser that includes a subcoolerpositioned external to the condenser shell. Positioning the subcoolerexternal to the shell of the condenser may enable the condenser toinclude a reduced level of refrigerant, while providing substantiallythe same amount of subcooling to the refrigerant. Additionally, a sizeof the condenser may be reduced while including the same amount of tubesbecause the subcooler is positioned external to the shell of thecondenser. Reducing the size of the condenser may reduce costs and afootprint of the overall vapor compression system. Further, positioningthe subcooler external to the subcooler shell may simplifymanufacturing, which may also lead to reduced costs.

Turning now to the drawings, FIG. 1 is a perspective view of anembodiment of an environment for a heating, ventilation, airconditioning, and refrigeration (HVAC&R) system 10 in a building 12 fora typical commercial setting. The HVAC&R system 10 may include a vaporcompression system 14 that supplies a chilled liquid, which may be usedto cool the building 12. The HVAC&R system 10 may also include a boiler16 to supply warm liquid to heat the building 12 and an air distributionsystem which circulates air through the building 12. The airdistribution system can also include an air return duct 18, an airsupply duct 20, and/or an air handler 22. In some embodiments, the airhandler 22 may include a heat exchanger that is connected to the boiler16 and the vapor compression system 14 by conduits 24. The heatexchanger in the air handler 22 may receive either heated liquid fromthe boiler 16 or chilled liquid from the vapor compression system 14,depending on the mode of operation of the HVAC&R system 10. The HVAC&Rsystem 10 is shown with a separate air handler on each floor of building12, but in other embodiments, the HVAC&R system 10 may include airhandlers 22 and/or other components that may be shared between or amongfloors.

FIGS. 2 and 3 are embodiments of the vapor compression system 14 thatcan be used in the HVAC&R system 10. The vapor compression system 14 maycirculate a refrigerant through a circuit starting with a compressor 32.The circuit may also include a condenser 34, an expansion valve(s) ordevice(s) 36, and a liquid chiller or an evaporator 38. The vaporcompression system 14 may further include a control panel 40 that has ananalog to digital (A/D) converter 42, a microprocessor 44, anon-volatile memory 46, and/or an interface board 48.

Some examples of fluids that may be used as refrigerants in the vaporcompression system 14 are hydrofluorocarbon (HFC) based refrigerants,for example, R-410A, R-407, R-134a, hydrofluoro olefin (HFO), “natural”refrigerants like ammonia (NH₃), R-717, carbon dioxide (CO₂), R-744, orhydrocarbon based refrigerants, water vapor, or any other suitablerefrigerant. In some embodiments, the vapor compression system 14 may beconfigured to efficiently utilize refrigerants having a normal boilingpoint of about 19 degrees Celsius (66 degrees Fahrenheit) at oneatmosphere of pressure, also referred to as low pressure refrigerants,versus a medium pressure refrigerant, such as R-134a. As used herein,“normal boiling point” may refer to a boiling point temperature measuredat one atmosphere of pressure.

In some embodiments, the vapor compression system 14 may use one or moreof a variable speed drive (VSDs) 52, a motor 50, the compressor 32, thecondenser 34, the expansion valve or device 36, and/or the evaporator38. The motor 50 may drive the compressor 32 and may be powered by avariable speed drive (VSD) 52. The VSD 52 receives alternating current(AC) power having a particular fixed line voltage and fixed linefrequency from an AC power source, and provides power having a variablevoltage and frequency to the motor 50. In other embodiments, the motor50 may be powered directly from an AC or direct current (DC) powersource. The motor 50 may include any type of electric motor that can bepowered by a VSD or directly from an AC or DC power source, such as aswitched reluctance motor, an induction motor, an electronicallycommutated permanent magnet motor, or another suitable motor.

The compressor 32 compresses a refrigerant vapor and delivers the vaporto the condenser 34 through a discharge passage. In some embodiments,the compressor 32 may be a centrifugal compressor. The refrigerant vapordelivered by the compressor 32 to the condenser 34 may transfer heat toa cooling fluid (e.g., water or air) in the condenser 34. Therefrigerant vapor may condense to a refrigerant liquid in the condenser34 as a result of thermal heat transfer with the cooling fluid. Theliquid refrigerant from the condenser 34 may flow through the expansiondevice 36 to the evaporator 38. In the illustrated embodiment of FIG. 3,the condenser 34 is water cooled and includes a tube bundle 54 connectedto a cooling tower 56, which supplies the cooling fluid to thecondenser.

The liquid refrigerant delivered to the evaporator 38 may absorb heatfrom another cooling fluid, which may or may not be the same coolingfluid used in the condenser 34. The liquid refrigerant in the evaporator38 may undergo a phase change from the liquid refrigerant to arefrigerant vapor. As shown in the illustrated embodiment of FIG. 3, theevaporator 38 may include a tube bundle 58 having a supply line 60S anda return line 60R connected to a cooling load 62. The cooling fluid ofthe evaporator 38 (e.g., water, ethylene glycol, calcium chloride brine,sodium chloride brine, or any other suitable fluid) enters theevaporator 38 via return line 60R and exits the evaporator 38 via supplyline 60S. The evaporator 38 may reduce the temperature of the coolingfluid in the tube bundle 58 via thermal heat transfer with therefrigerant. The tube bundle 58 in the evaporator 38 can include aplurality of tubes and/or a plurality of tube bundles. In any case, thevapor refrigerant exits the evaporator 38 and returns to the compressor32 by a suction line to complete the cycle.

FIG. 4 is a schematic of the vapor compression system 14 with anintermediate circuit 64 incorporated between condenser 34 and theexpansion device 36. The intermediate circuit 64 may have an inlet line68 that is directly fluidly connected to the condenser 34. In otherembodiments, the inlet line 68 may be indirectly fluidly coupled to thecondenser 34. As shown in the illustrated embodiment of FIG. 4, theinlet line 68 includes a first expansion device 66 positioned upstreamof an intermediate vessel 70. In some embodiments, the intermediatevessel 70 may be a flash tank (e.g., a flash intercooler). In otherembodiments, the intermediate vessel 70 may be configured as a heatexchanger or a “surface economizer.” In the illustrated embodiment ofFIG. 4, the intermediate vessel 70 is used as a flash tank, and thefirst expansion device 66 is configured to lower the pressure of (e.g.,expand) the liquid refrigerant received from the condenser 34. Duringthe expansion process, a portion of the liquid may vaporize, and thus,the intermediate vessel 70 may be used to separate the vapor from theliquid received from the first expansion device 66. Additionally, theintermediate vessel 70 may provide for further expansion of the liquidrefrigerant because of a pressure drop experienced by the liquidrefrigerant when entering the intermediate vessel 70 (e.g., due to arapid increase in volume experienced when entering the intermediatevessel 70). The vapor in the intermediate vessel 70 may be drawn by thecompressor 32 through a suction line 74 of the compressor 32. In otherembodiments, the vapor in the intermediate vessel may be drawn to anintermediate stage of the compressor 32 (e.g., not the suction stage).The liquid that collects in the intermediate vessel 70 may be at a lowerenthalpy than the liquid refrigerant exiting the condenser 34 because ofthe expansion in the expansion device 66 and/or the intermediate vessel70. The liquid from intermediate vessel 70 may then flow in line 72through a second expansion device 36 to the evaporator 38.

As discussed above, a condenser that includes an external subcooler mayenhance an efficiency of the vapor compression system 14 and/or reducecosts of the vapor compression system 14. For example, FIG. 5 is aperspective view of the condenser 34 that includes an external subcooler100. As shown in the illustrated embodiment of FIG. 5, the subcooler 100may be a shell portion 102 (e.g., tube portion) that is configured toreceive refrigerant 104 from a shell 108 of the condenser 34, where theshell 108 includes tubes 106 configured to be place a cooling fluid in aheat exchange relationship with the refrigerant 104. The shell portion102 may resemble a half pipe or a conduit that includes a semi-circularcross section. In other embodiments, the shell portion 102 may be anysuitable portion of a tube or conduit formed by cutting the tube orconduit along an intersection 110 of the tube or conduit with a plane orsubstantially planar surface 112 that enables edges 114 of the shellportion 102 to be secured along an outer surface 116 (e.g., acircumference) of the shell 108 of the condenser 34 (e.g., via weldingor another suitable technique that couples the shell portion 102 to theouter surface 116 of the shell 108). In other words, the subcooler 100is positioned external to the shell 108 of the condenser 34.

Openings 118 formed in the shell 108 are positioned so as to be in fluidcommunication with and covered by the shell portion 102, such that therefrigerant 104 flows from the shell 108 into the shell portion 102.Cooling fluid flowing through tubes 120 extending through a shell 121 ofthe shell portion 102 may exchange thermal energy with the refrigerant104 surrounding the tubes 120. In some embodiments, the cooling fluidflowing through the tubes 120 is the same as the cooling fluid flowingthrough the tubes 106 of the condenser 34 (e.g., water), but at a lowertemperature than the cooling fluid flowing through the tubes 106 of thecondenser 34. Accordingly, the tubes 120 of the shell portion 102 maysupercool the refrigerant 104 and increase a cooling capacity of thesystem 14. Such an increase in system cooling capacity may be achievedwhile minimizing an amount of refrigerant used in the condenser 34. Insome embodiments, a length 122 of the shell portion 102 can besubstantially equal to a length 124 of the shell 108. However in otherembodiments, the lengths 122 and 124 may be different from one another.

FIG. 6 is a cross section of an embodiment of the condenser 34 thatincludes the external subcooler 100, and FIG. 7 is a perspective view ofthe condenser 34 of FIG. 6. As shown in the illustrated embodiments ofFIGS. 6 and 7, the subcooler 100 is external from the shell 108 of thecondenser 34 and includes a substantially rectangular cross-section. Thecondenser 34 may include an inlet 140 that receives refrigerant (e.g.,from the compressor 32) and directs the refrigerant into the shell 108of the condenser 34. In some embodiments, the condenser 34 may includean impingement plate 142 that is configured to enhance distribution ofthe refrigerant over the tubes 106 of the condenser 34. As shown in theillustrated embodiments of FIGS. 6 and 7, the impingement plate 142 maybe substantially aligned with the inlet 140. However, in otherembodiments, the impingement plate 142 may be positioned in anothersuitable location within the shell 108 of the condenser 34.Additionally, the condenser 34 of FIGS. 6 and 7 has a first bundle 144of the tubes 106 and a second bundle 146 of the tubes 106, where thefirst bundle 144 and the second bundle 146 are separated by a gap 148that does not include any of the tubes 106. In some embodiments,separating the first bundle 144 and the second bundle 148 by the gap 148may further enhance distribution of the refrigerant in the condenser 34by enabling high pressure concentrations (e.g., pockets) of therefrigerant to be dispersed.

As shown in the illustrated embodiments of FIGS. 6 and 7, the shell 121of the subcooler 100 is directly coupled to the shell 108 of thecondenser 34. The shell 121 of the subcooler 100 is disposed over theopening 118 of the shell 108, such that refrigerant from the condenser34 enters the subcooler 100 via the opening 118. The refrigerantentering the subcooler 100 may pass over the tubes 120, which may flow acooling fluid that is at a lower temperature than a cooling fluid in thetubes 106 of the condenser 34. Accordingly, the refrigerant may besubcooled as thermal energy is transferred from the refrigerant to thecooling fluid in the tubes 120 as the refrigerant 26 passes over thetubes 120.

In some embodiments, the subcooler 100 may include a partition plate 150that separates the tubes 120 of the subcooler 100 to create two or moreflow paths for the refrigerant within the subcooler 100 (see e.g., FIG.8). Increasing an amount of flow paths for the refrigerant in thesubcooler 100 may improve an efficiency of the subcooler 100 by exposingthe refrigerant to more of the tubes 120. Regardless of the flow path inwhich the refrigerant takes through the subcooler 100, the refrigerantmay ultimately exit the subcooler 100 through an outlet 152 that isconnected to a bottom portion 154 of the subcooler shell 121.

FIG. 8 is a cross section of the condenser 34 that illustrates a firstflow path 170 and a second flow path 172 of the refrigerant through theexternal subcooler 100 when the subcooler 100 includes the partitionplate 150. For example, the partition plate 150 and an inner wall 174 ofthe subcooler shell 121 may act to direct the refrigerant along both thefirst flow path 170 and the second flow path 172. While the illustratedembodiment of FIG. 8 shows the subcooler 100 having two refrigerant flowpaths, it should be noted that the subcooler 100 may have onerefrigerant flow path or more than two refrigerant flow paths (e.g.,three, four, five, six, seven, eight, nine, ten, or more refrigerantflow paths).

As shown in the illustrated embodiment of FIG. 8, the refrigerant entersthe condenser 34 from the inlet 140, passes through the impingementplate 142, and exchanges heat with the tubes 106 of the condenser 34 tocondense the refrigerant into a liquid (e.g., the refrigerant flows froma top 176 of the condenser 34 to a bottom 178 of the condenser 34outside of the tubes 106). The liquid refrigerant may collect at thebottom 178 of the condenser 34 and enter the subcooler 100 through theopening 118. The refrigerant may be directed through the subcooler 100along the first flow path 170 or the second flow path 172 from theopening 118 to the outlet 152 of the subcooler 100. As shown in theillustrated embodiment of FIG. 8, the refrigerant that flows along thefirst flow path 170 may be directed from the opening 118 toward theinner wall 174 in a first direction 180 and the refrigerant that flowsalong the second flow path 172 may be directed from the opening 118toward the inner wall 174 in a second direction 182, opposite the firstdirection 180. Once the refrigerant reaches the inner wall 174, therefrigerant that flows along the first flow path 170 may be directedfrom the inner wall 174 to the outlet 152 in the second direction 182and the refrigerant that flows along the second flow path 172 may bedirected from the inner wall 174 to the outlet 152 in the firstdirection 180. Regardless of which flow path the refrigerant flowsalong, the refrigerant exchanges thermal energy with the cooling fluidin the tubes 120 of the subcooler 100 to reduce a temperature of therefrigerant and/or subcool the refrigerant. Directing the refrigerantalong multiple flow paths may increase an amount of thermal energytransferred from the refrigerant by increasing an amount of the tubes120 with which the refrigerant contacts.

It should be noted that the refrigerant does not substantially collect(e.g., pool) within the shell 108 of the condenser 34 in order toachieve subcooling when the subcooler 100 is external to the shell 108.Accordingly, substantially the same degree of subcooling may be achievedwhen the subcooler 100 is external to the shell 108 as compared tocondenser configurations that include internal subcoolers. However, lessrefrigerant charge (e.g., collected refrigerant) may be present inembodiments having the external subcooler 100. Moreover, the externalsubcooler 100 may enable the condenser shell 108 to include the samenumber of tubes 106 as a condenser with an internal subcooler, butinclude a smaller diameter, thereby reducing costs. Further, because theexternal subcooler 100 may be separately manufactured from the condenser34, manufacturing the condenser 34 may be less complex, time-consuming,and/or expensive.

In some embodiments, the condenser 34 that includes the externalsubcooler 100 may be a dual-pass heat exchanger, which may furtherenhance an efficiency of the condenser 34. For example, FIG. 9 is across section of an embodiment of the condenser 34 that is configured tooperate as a dual-pass heat exchanger. As shown in the illustratedembodiment of FIG. 9, the condenser 34 includes tube plates 200, a firstwater tank 202, and a second water tank 204 disposed at ends 206 of thecondenser shell 108 and ends 208 the subcooler shell 121. The ends 208of the subcooler shell 121 may be coupled to the tube plates 200 suchthat cooling fluid flowing through the tubes 120 of the subcooler 100 isblocked from leaking outside of the subcooler shell 121.

The condenser 34 may include a partition plate 210 that separates thetubes 106 of the condenser 34 into first pass tubes 212 and second passtubes 214. As shown in the illustrated embodiment of FIG. 9, the firstpass tubes 212 are disposed below the partition plate 210 with respectto the inlet 140 and the second pass tubes 214 are disposed above thepartition plate 210 with respect to the inlet 140. The first pass tubes212 may thus contact the refrigerant after the refrigerant has contactedthe second pass tubes 214. Additionally, because the first pass tubes212 may flow cooling fluid that is at a lower temperature than thesecond pass tubes 214, an efficiency of the condenser 34 may beenhanced.

Cooling fluid may enter the first water tank 202 from a cooling fluidinlet 216. A first portion 218 of the cooling fluid enters the subcooler100 and a second portion 220 of the cooling fluid enters the first passtubes 212 of the condenser 34. In some embodiments, the cooling fluidexiting both the tubes 120 of the subcooler 100 and the first pass tubes212 may mix in the second water tank 204 before being directed into thesecond pass tubes 214. However, in other embodiments, the cooling fluidfrom the tubes 120 of the subcooler 100 may be directed to anotherlocation (e.g., back to the inlet 216). Upon exiting the first passtubes 212, the cooling fluid may exit the condenser 34 via an outlet222, which may direct the cooling fluid to a cooling tower or anothersuitable location.

In the embodiments of FIGS. 5-9, the condenser shell 108 and thesubcooler shell 121 may be welded together. As such, the condenser 34and the subcooler 100 may initially be two separate members, which maybe manufactured respectively and connected together by conventionalmethods (e.g., welding), thus facilitating and/or simplifyingmanufacturing of the system 14.

While the illustrated embodiments of the subcooler 100 of FIGS. 5-9 mayinclude the shell portion 102 (i.e., FIG. 5) and/or a rectangular crosssection (e.g., FIGS. 6-9), the subcooler 100 may include any othersuitable shape. For example, FIG. 10 is a cross section of the condenser34 having the subcooler 100 that is includes a curved cross section,such that the subcooler 100 conforms to the outer surface 116 of thecondenser shell 108. Additionally, the subcooler 100 of FIG. 10 mayinclude the partition plate 150, which may also include a curvature(e.g., an arc shape), such that the partition plate 150 mirrors a crosssection of the subcooler 100. Additionally, the tubes 120 within thesubcooler 100 may be arranged with the curvature of the subcooler 100cross section. In some embodiments, the curved subcooler 100 of FIG. 10may reduce a welding area between the subcooler shell 121 and thecondenser shell 108, to further facilitate manufacturing.

In still further embodiments, the subcooler 100 may be external to thecondenser 34 and coupled to the condenser shell 108 without a directweld or other abutment. For example, FIG. 11 is a cross section of anembodiment of the condenser 34 that includes the subcooler 100 coupledto the condenser shell 108 by an intermediate conduit 240 coupled to theopening 118 and an inlet 242 of the subcooler 100. Accordingly, a gap244 is formed between the condenser shell 108 and the subcooler shell121 by the intermediate conduit 240. Indeed, welds may ultimately couplethe condenser shell 108 to the intermediate conduit 240 and thesubcooler shell 121 to the intermediate conduit 240, but the condensershell 108 and the subcooler shell 121 may not be directly welded to oneanother.

While the illustrated embodiment of FIG. 11 shows the condenser 34having a single intermediate conduit 240, it should be recognized thatmore than one intermediate conduit 240 may be included to couple thecondenser 34 to the subcooler 100 (e.g., two, three, four, five, six,seven, eight, nine, ten, or more intermediate conduits 240).Additionally, the intermediate conduit 240 of FIG. 11 is positionedalong a central axis 246 of the condenser 34 (and/or the subcooler 100).However, in other embodiments, the intermediate conduit 240 may bepositioned at any suitable location along the condenser shell 108 thatsufficiently couples the condenser 34 to the subcooler 100. In someembodiments, the intermediate conduit 240 may be a cylindrical pipe. Inother embodiments, the intermediate conduit 240 may include any suitablyshaped conduit that directs refrigerant from the condenser 34 to thesubcooler 100.

While only certain features and embodiments have been illustrated anddescribed, many modifications and changes may occur to those skilled inthe art (e.g., variations in sizes, dimensions, structures, shapes andproportions of the various elements, values of parameters (e.g.,temperatures, pressures, etc.), mounting arrangements, use of materials,colors, orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter recited in the claims.The order or sequence of any process or method steps may be varied orre-sequenced according to alternative embodiments. It is, therefore, tobe understood that the appended claims are intended to cover all suchmodifications and changes as fall within the true spirit of thedisclosure. Furthermore, in an effort to provide a concise descriptionof the exemplary embodiments, all features of an actual implementationmay not have been described (i.e., those unrelated to the presentlycontemplated best mode of carrying out the disclosure, or thoseunrelated to enabling the claimed disclosure). It should be appreciatedthat in the development of any such actual implementation, as in anyengineering or design project, numerous implementation specificdecisions may be made. Such a development effort might be complex andtime consuming, but would nevertheless be a routine undertaking ofdesign, fabrication, and manufacture for those of ordinary skill havingthe benefit of this disclosure, without undue experimentation.

1. A vapor compression system comprising: a refrigerant loop; acompressor disposed along the refrigerant loop and configured tocirculate refrigerant through the refrigerant loop; a condenser disposeddownstream of the compressor along the refrigerant loop and configuredto condense vapor refrigerant to liquid refrigerant; a subcooler coupledto the condenser, wherein the subcooler is external to a shell of thecondenser, and wherein the subcooler is configured to receive the liquidrefrigerant from the condenser and to cool the liquid refrigerant tosubcooled refrigerant; and an evaporator disposed downstream of thesubcooler along the refrigerant loop and configured to evaporate thesubcooled refrigerant into the vapor refrigerant.
 2. The vaporcompression system of claim 1, wherein the subcooler comprises asubcooler shell, and wherein a plurality of tubes configured to flow acooling fluid are disposed within the subcooler shell.
 3. The vaporcompression system of claim 2, wherein the condenser comprises aplurality of additional tubes configured to flow the cooling fluid, andwherein the plurality of additional tubes are disposed in the shell ofthe condenser.
 4. The vapor compression system of claim 3, wherein thesubcooler shell is welded directly onto the shell of the condenser. 5.The vapor compression system of claim 4, wherein the subcooler shellincludes a curved cross section conforming to the shell of thecondenser.
 6. The vapor compression system of claim 3, wherein thesubcooler shell is coupled to an opening in the shell of the condenserby an intermediate conduit.
 7. The vapor compression system of claim 6,wherein the intermediate conduit forms a gap between the subcooler shelland the shell of the condenser.
 8. The vapor compression system of claim1, wherein the subcooler comprises a partition plate configured todirect the refrigerant entering the subcooler along a first flow pathand a second flow path.
 9. The vapor compression system of claim 1,wherein the condenser is a dual pass heat exchanger comprising apartition plate, wherein the condenser comprises a first water tankconfigured to direct cooling fluid into first pass tubes of thecondenser and subcooler tubes of the subcooler and a second water tankconfigured to direct cooling fluid exiting the first pass tubes and thesubcooler tubes of the subcooler into second pass tubes of thecondenser.
 10. The vapor compression system of claim 9, wherein thefirst water tank is configured to direct the cooling fluid from thesecond pass tubes out of the condenser.
 11. A subcooler, comprising: ashell; a plurality of tubes, wherein the plurality of tubes are disposedwithin the shell; and an inlet disposed on the shell and configured todirect condensed refrigerant from a condenser into the subcooler; andwherein the subcooler is configured to be coupled to an outer shell ofthe condenser.
 12. The subcooler of claim 11, comprising the condenser,wherein the shell is welded directly to the outer shell of thecondenser.
 13. The subcooler of claim 11, comprising the condenser,wherein the inlet is coupled to an outlet disposed in the outer shell ofthe condenser by an intermediate conduit.
 14. The subcooler of claim 11,comprising a partition plate configured to direct refrigerant enteringthe subcooler along a first flow path and a second flow path.
 15. Avapor compression system, comprising: a refrigerant loop; a compressordisposed along the refrigerant loop and configured to circulaterefrigerant through the refrigerant loop; a condenser disposeddownstream of the compressor along the refrigerant loop, wherein thecondenser comprises a shell and a first plurality of tubes disposed inthe shell, wherein the first plurality of tubes is configured to flow afirst cooling fluid, and wherein the first cooling fluid is configuredto be in a heat exchange relationship with the refrigerant; a subcoolercoupled directly to an outer surface of the shell of the condenser orcoupled indirectly to the outer surface of the shell of the condenser,wherein the subcooler comprises a subcooler shell and a second pluralityof tubes configured to flow a second cooling fluid, and wherein thesecond cooling fluid is configured to be in a heat exchange relationshipwith the refrigerant; and an evaporator disposed downstream of thesubcooler along the refrigerant loop.
 16. The vapor compression systemof claim 15, wherein the first cooling fluid and the second coolingfluid both comprise water.
 17. The vapor compression system of claim 15,wherein the subcooler comprises a partition plate configured to separatethe second plurality of tubes into a third plurality of tubes and afourth plurality of tubes, and wherein the refrigerant is configured toflow through the subcooler along a first flow path and a second flowpath at least partially defined by the partition plate.
 18. The vaporcompression system of claim 15, wherein subcooler shell is weldeddirectly to the outer surface of the shell of the condenser.
 19. Thevapor compression system of claim 15, wherein the subcooler shell iswelded to an intermediate conduit that is coupled to an outlet of thecondenser.
 20. The vapor compression system of claim 15, wherein therefrigerant has a normal boiling point of up to 66 degrees Fahrenheit.